function Link_Cov=GetLinkCov(file_name, sample_size)
  Link_Cov = [];
  f_id = fopen(file_name);
  while ~feof(f_id)
    line = fgetl (f_id);
    delay_records = str2num (line);
    delay_records = delay_records(find(delay_records >0));
    [m,n] = size(delay_records);
    columns = 3:1:n; % remove the sender id
    [x,y]=size(columns); % 1, 5679
    if y < sample_size
      continue;
    end
    if y ~= 0
        %selected_columns = ceil(rand(1,sample_size) * y);
        Link_Cov= [Link_Cov, std(delay_records(columns)) / mean(delay_records(columns))];
        %Link_Cov= [Link_Cov, (prctile(delay_records, 75)-  prctile(delay_records,25))/2];
    end

  end
  fclose(f_id);

end
